Four years ago we began soliciting articles for this volume from authors who were engaged in comprehensive research on whales. From the outset we decided not to limit the subject matter to behavior but to also include natural history. Much of what is known about the behavior of whales arose from studies whose principal aim was not behavior, much as it did for other animal groups before behavior was considered a distinct discipline. Thus in many of the articles behavior is closely intertwined with natural history and in others is completely overshadowed by a basic natural history approach. Our aim was to have the articles contain a review of the literature and include research findings not previously published. For all intents and purposes this aim has been realized, albeit perhaps not in as balanced a fashion in terms of species or subject matter as was originally planned. Nevertheless, we believe the articles present a wide range of informative works with a myriad of approaches and techniques represented. We are grateful to the contributors for their patience and understanding in awaiting publication, which has taken much longer than we originally expected. We are also grateful tor the assistance of a number of people, especially Julie Fischer and Lois Winn for their editorial efforts, and Jill Grover, Carol Samet, and Lois Winn for their help in indexing.